The term accuracy is used in all scientific fields and is synonymous with precision and exactness. It is a dimensionless value expressed as a percentage. Inmetrology, accuracy is the percentage value of a deviation in relation to the nominal value.
The term accuracy occurs in many technical applications; in mechanics and construction, electronics, metrology and communications, analog technology and digital technology. However, it always refers to the tolerance deviations and limits of technical parameters or characteristics. The accuracy is determined from the quotient of the deviation and the nominal value. For example, if the deviation is 1 and the nominal value is 100, the accuracy is 99%.
Since the measuring instruments used in metrology are not one hundred percent accurate, but have a measuring inaccuracy themselves, the measured accuracy cannot be higher than the measuring accuracy of the measuring instrument. Therefore, measuring devices are classified into accuracy classes.